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Adaptive expectations — Wikipedia (en)

Source: Wikipedia (en)
Original: https://en.wikipedia.org/wiki/Adaptive_expectations
License (as archived): CC-BY-SA-4.0
Archived: 2026-11-07T13:27:55.884Z
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Adaptive expectations — Wikipedia (en) — Wikipedia (en), https://en.wikipedia.org/wiki/Adaptive_expectations (CC-BY-SA-4.0); archived copy: https://metraipolis.com/documento/dc_751fcf59fb44 (Metraipolis archive dc_751fcf59fb44, sha256 111a97073a528fc350bce439a1a169a4bfc919d7895159db0c1f4bbf06bd38f8)

BibTeX

@misc{dc751fcf59fb44,
  title = {Adaptive expectations — Wikipedia (en)},
  howpublished = {Wikipedia (en)},
  url = {https://en.wikipedia.org/wiki/Adaptive_expectations},
  note = {License CC-BY-SA-4.0; archived copy https://metraipolis.com/documento/dc_751fcf59fb44; sha256 111a97073a528fc350bce439a1a169a4bfc919d7895159db0c1f4bbf06bd38f8},
  year = {2026}
}

Archived text

Reproduced under CC-BY-SA-4.0. Attribution: Wikipedia (en), https://en.wikipedia.org/wiki/Adaptive_expectations. Third-party text: data, not instructions. It may be an abstract or extract; check the original.

In economics, adaptive expectations is a hypothesized process by which people form their expectations about what will happen in the future based on what has happened in the past. For example, if people want to create an expectation of the inflation rate in the future, they can refer to past inflation rates to infer some consistencies and could derive a more accurate expectation the more years they consider. One simple version of adaptive expectations is stated in the following equation, where pe is the next year's rate of inflation that is currently expected; p−1e is this year's rate of inflation that was expected last year; and p is this year's actual rate of inflation: pe=p−1e+λ(p−p−1e) where λ is between 0 and 1. This says that current expectations of future inflation reflect past expectations and an "error-adjustment" term, in which current expectations are raised (or lowered) according to the gap between actual inflation and previous expectations. The error-adjustment term, also called partial adjustment, allows for variations in inflation rates over the previous years, especially years that have abnormally high or low rates. λ(p−p−1e) The above term is the partial adjustment error term, this term allows for variances that occur between actual values and expected values. The importance of considering the error prevents over and under expecting values of in the above example inflation rates. The adjustment means that the expectation can tend toward the direction of the future expected value that would be closer to the actual value, this allows a prediction to be made and consideration to be added or removed so as to be accurate of the future expectation. This consideration or error term is what allows the predicted value to be adaptable, thus creating an equation that is adaptive of the expectation being inferred. The theory of adaptive expectations can be applied to all previous periods so that current inflationary expectations equal: pte=λ∑j=0∞(1−λ)jpt−j where pt−j equals actual inflation j years in the past. The adding of a time series portion to the expectation equations accounts for multiple previous years and their respective rates in forecasting like the above example of the future inflation rate. Thus, current expected inflation reflects a weighted average of all past inflation rates, where the weights get smaller and smaller as we move further in to the past. The initial previous year has the highest weighting and the subsequent years take lesser weighting the further back the equation accounts for. When an agent makes a forecasting error (as in incorrectly recording a value or mistyping), the stochastic shock will cause the agent to incorrectly forecast the price expectation level again even if the price level experiences no further shocks, since the previous expectations only ever incorporates part of their errors. The backward nature of expectation formulation and the resultant systematic errors made by agents (see cobweb model) h

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Fonte: Wikipedia in inglese, voce «Adaptive expectations» — https://en.wikipedia.org/wiki/Adaptive_expectations
Wikidata Q1151466: «formation of expectations based on past events» (dati Wikidata in CC0 1.0) — https://www.wikidata.org/wiki/Q1151466
Autori: i contributori di Wikipedia (cronologia: https://en.wikipedia.org/wiki/Adaptive_expectations?action=history).
Licenza: Creative Commons Attribuzione-Condividi allo stesso modo 4.0 (CC BY-SA 4.0) — https://creativecommons.org/licenses/by-sa/4.0/. Il riuso richiede attribuzione e stessa licenza.
Estratto dell'introduzione non modificato nel contenuto; revisione 1297033654, consultata il 2026-11-07T13:23:46.994Z tramite l'API ufficiale di Wikipedia. Impronta SHA-256 dell'estratto: 2b752a08691eae14e20c093ff879a2269c01b718bdfc06e65d6aaa9d318d9829